Conventional nail lacquer compositions rely on nitrocellulose as the primary film former. While nitrocellulose is the film former of choice, it has numerous disadvantages. For example, nitrocellulose discolors with age, is prone to undergo sharp viscosity changes rendering nail lacquer compositions difficult to apply, and it can be difficult to dry to a hard film. Furthermore, car must be taken to insure that nitrocellulose used in formulating nail lacquers is neutral, i.e., acid free, because the presence of free acid could cause damage to fingernails and the cuticle, as well as have a deleterious effect on colorants present in nail lacquers.
Of course, those skilled in the art recognize that nitrocellulose must be produced and handled with great caution and care. The danger of explosion and fire inherent in nitrocellulose production and formulation of compositions containing nitrocellulose is responsible in large measure for the fact that there are very few domestic manufacturers of this product, and only a few domestic formulators of nail lacquers.
The art has frequently sought substitutes for nitrocellulose as a film former for nail lacquers. Attempts to find substitutes for nitrocellulose have not been successful, because, despite its many drawbacks, nitrocellulose provides nail lacquer compositions with an unusual combination of desirable properties such as toughness, durability and solvent release, and it produces waterproof and atmospherically stable films. For examples of such attempts see U.S. Pat. Nos. 3,840,490; 3,864,294; 3,927,203; 3,298,113 and 4,240,450. Typical nitrocellulose containing nail lacquer compositions are described in U.S. Pat. Nos. 4,097,589 and 4,179,304, for example.
There is, therefore, a long felt need in the art for a product which can be substituted for nitrocellulose in the formulation of nail lacquer compositions which will result in finished nail lacquers which are the equivalent of nitrocellulose containing lacquers.
In addition to nitrocellulose film formers, conventional nail lacquer compositions include a resin, plasticizer, solvent and pigments. Plasticizers function to reduce film shrinkage with drying and to give the film flexibility. Solvents provide the lacquer with properties permitting ease of application and affect the rate of drying of the lacquer after application. Pigments or colorants provide the desired color to the nail lacquer.